Code 39 Barcode FAQ and Tutorial

• Overview
• Printing and Generating Code 39 Barcodes
• Reading Code 39 Barcodes
• Mod43 Check Character Calculation
• Encoding Functions
• Extended ASCII Table
• If a scanner is needed, IDAutomation also provides hand-held barcode scanner kits.

Code 39 is a common barcode type used for various labels such as name badges, inventory and industrial applications. The symbology of the Code 39 character set consists of barcode symbols representing characters 0-9, A-Z, the space character and the following symbols: - . $ / + %. In addition, the full 128 ASCII character set can be encoded in Code 39.

The Code 39 barcode is the easiest of the alpha-numeric barcodes to use and is designed for character self-checking, thus eliminating the need for check character calculations. Code 39 is also known as the 3 of 9 Barcode, Code 3 of 9, Bar Code 39 and more. Several standards exist that dictate how Code 39 barcodes should be printed for certain implementations. Although a checksum character is optional, many standards require it. The checksum character is a type of MOD43 calculation provided in many of the IDAutomation font tools for the Code 39 Barcode Fonts. Enabling the check digit option in IDAutomation Barcode Components and Applications allows the component to automatically generate and include the MOD43 checksum.

The following standards based on the 3 of 9 barcode require MOD43 check digits:

• LOGMARS (Logistics Applications of Automated Marking and Reading Symbols) is a standard based on Code 39 used by the United States Department of Defense. LOGMARS is defined by Military Standard MIL-STD-1189B and others such as MIL-STD-129, MIL-STD-2073-1C and MIL-STD-129N.
• HIBC (Health Industry Barcode) is a barcode label used in the health care product industry. Several implementations of HIBC also use Code 128.

The complete Code 39 barcode consists of a start character, data digits, an optional check character and a stop character.

Start Character	Data Digits	Optional Check Character	Stop Character
*	CODE-39	P	*

The Code 39 asterisk character is usually used as a start/stop character, and should not be part of the data in the barcode. The asterisk may be used as the start/stop character with fonts; however, this may cause problems in some applications such as MS Word, because they may treat text surrounded with asterisks as bold text. In IDAutomation Code 39 barcode fonts, the exclamation and parentheses characters are also used as start/stop characters to avoid these problems and provide additional functionality.

Printing of the Code 39 barcode as a font is an easy process if checksum characters are not required for the implementation. If the checksum is needed, IDAutomation provides several Font Tools, Components and Applications for this purpose.

IDAutomation Code 39 Barcode Fonts may be created directly from the keyboard or used in a calculated field to dynamically produce multiple symbols in almost any application, including Microsoft Word, Excel, FileMaker, QuickBooks and OpenOffice. To create a 3 of 9 barcode manually that encodes the data "BAR-CODE-39", the following may be performed:
    1. Select the IDAutomation Code 39 Barcode Font from the list of installed fonts;
    2. Type the start character of "*";
    3. Enter the data to be encoded, which is "BAR-CODE-39";
    4. Type the stop character of "*"

When the IDAutomation Code 39 Barcode Font is used, the parenthesis may be used as the start and stop characters to keep the asterisks from appearing in the text interpretation. For example, (BAR-CODE-39).

Several Barcode Integration Guides are also available that suggest one or more barcode 39 printing options. These integration options should be examined to determine whether to use barcode components, applications or fonts for the printing of barcodes. A few of the Barcode Integration Guides offered include the following:

• Access
• Crystal Reports
• Excel
• FileMaker
• Open Office & Star Office
• Oracle Reports
• Reporting Services
• C++
• C# .NET
• Visual Basic 6 and VB.NET
• Web Barcode Implementation

The most common method of reading barcodes is with a barcode scanner. Most barcode scanners recommended by IDAutomation perform keyboard emulation and receive power from the USB port, so that no external power supply is required. When a barcode is scanned using keyboard emulation, the data scanned appears at the cursor as if it had been typed in from the keyboard.

Most barcode scanners have the ability to read Code 39 barcodes by default, such as the IDAutomation USB Barcode Scanner. This scanner dependably reads the IDAutomation Code 39 Barcode Font and Universal Barcode Font when printed as small as 6 points, which is an X dimension of 4 mils.

The manual calculations described below are rarely necessary. IDAutomation provides several barcode font tools, plug-ins and source code samples that are free to use with IDAutomation fonts, which automatically format the start, stop and check characters to the barcode fonts. Additionally, the check digit option in all Components and Applications calculates and includes the checksum automatically.

Perform the following to calculate the optional modulus 43 check character manually:

1. Using the table below, obtain the number value of each data character.
2. Add all of these values together.
3. Divide the total by 43 and obtain the remainder.
4. The check character is the value of the remainder.

For example, perform the following calculations to determine the check character using the data characters "CODE39":

1. The values are 12, 24, 13, 14, 3 and 9.
2. When added together, these total 75.
3. Now divide 75 by 43 and the remainder is 32.
4. The check character is W

Code 39 Character Values:

The full 128 ASCII character set can be printed in accordance with ISO 646. This may also be encoded in the Code 39 barcode font using combinations of two symbol characters made up of one of the four Code 39 characters (+ $ % / ) followed by one of the 26 Code 39 barcode alphabetic characters according to the Extended Code 39 ASCII Character Set. In order for Extended Code 39 to be decoded properly, the scanner must first be programmed to read it. Otherwise, the scanner will simply scan the existing data, for example "+C" instead of "c."

When extended Code 39 is enabled, functions may be directly encoded by using the format $? to specify the function where ? equals the character that represents the appropriate function in the Extended Code39 ASCII Character Set. For example, Code$I3of9$M will encode Code[TAB]3of9[RETURN].

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